Anti-atherogenic functions of high-density lipoproteins (HDL) include mediation of reverse cholesterol transport and reduction of oxidation and inflammation. Mounting evidence supports the concept that dysfunctional HDL loses its beneficial properties and actually contributes to the development of atherosclerosis. The central theme of our PPG is that HDL function is a critical determinant of atherogenesis and cardiovascular risk in chronic human disease. The goal of our research is to define the mechanisms for HDL functional loss in three diseases associated with increased risk for atherosclerotic cardiovascular disease: Familial Hypercholesterolemia (FH), Chronic Kidney Disease (CKD) and Rheumatoid Arthritis (RA). A major hypothesis of our proposal is that inflammation and oxidative stress impair HDL function. Plasma levels of F2-isoprostanes (F2-lsoP) are accurate in vivo markers of lipid peroxidation. Interestingly, HDL is the main carrier of F2-lsoP in plasma. Our studies in RA subjects suggest that F2-lsoP may be a biomarker for HDL function. Isolevuglandins (IsoLG) are a group of highly reactive mediators of oxidative damage that are formed as products of the IsoP pathway. We will examine the novel hypothesis that IsoLG forms adducts to HDL proteins and lipids, impairing HDL function. Subjects with FH have elevated levels of F2-lsoP and IsoLG protein adducts in their HDL and strikingly impaired anti-inflammatory HDL function. Chronic kidney disease (CKD) has been associated with increased plasma F2-lsoP levels and reduced cholesterol efflux capacity of HDL isolated from subjects with ESRD. HDL is also the major carrier of microRNAs (miRNAs) in plasma and delivers them to cells impacting gene expression. We will examine the novel hypothesis that the HDL-miRNA profile differs with disease state is altered by oxidative stress, and impacts HDL function. Projects 1 and 2 will examine mechanisms of dysfunctional HDL formation in FH and CKD, respectively. Project 3 will examine the impact of IsoP products on HDL function. The projects will rely heavily on Cores providing assays for HDL function, isoprostane products, miRNAs and bioinformatics. Ultimately, we aim to develop novel biomarkers and therapeutic approaches for dysfunctional HDL, shifting the clinical paradigm.